Methods for preparing devices having metallic hollow microchannels on planar substrate surfaces

A method for preparing cantilevered hollow metallic microchannels on a silicon substrate, said method comprising the steps of:

• a) forming a sacrificial membrane comprising p+ boron in a portion of a silicon substrate;
• b) depositing a first electroplating seed layer over a surface of said substrate having a sacrificial membrane portion;
• c) selectively electroplating said first electroplating seed layer with a selected metal to thereby form each metallic bottom wall of a microchannel;
• d) selectively coating a top surface of each said metallic bottom wall with a photoresist layer to a height corresponding to a selected inner height of each microchannel;
• e) depositing a second electroplating seed layer over said substrate having metallic bottom walls thereon;
• f) selectively electroplating said second electroplating seed layer with a selected metal to thereby form side walls and a top wall upon each bottom wall and surrounding said photoresist layer, said electroplating continuing until a desired thickness for said side walls and top walls is achieved;
• g) removing said photoresist layer from between the walls of each microchannel to thereby hollow each said microchannel;
• and
• h) removing said sacrificial membrane portion to thereby cantilever the portion of said metallic microchannels formed upon said sacrificial membrane portion of said silicon substrate.

A method for preparing hollow metallic microchannels on a substrate surface, said method comprising the steps of:

• a) depositing a first adhesion layer over a surface of a substrate;
• b) depositing a first electroplating seed layer over said first adhesion layer;
• c) depositing a second adhesion layer over said first electroplating seed layer;
• d) selectively coating said second adhesion layer with a first photoresist layer;
• e) removing portions of said second adhesion layer not coated by said first photoresist layer to thereby expose underlying portions of said first electroplating seed layer, each exposed portion of said first electroplating seed layer defining a location of a bottom wall of a microchannel;
• f) electroplating said exposed portions of said first electroplating seed layer with a selected metal to thereby form each metallic bottom wall of a microchannel;
• g) removing said first photoresist layer and portions of said second adhesion layer, said first electroplating seed layer, and said first adhesion layer underlying said first photoresist layer;
• h) selectively coating a top surface of each said metallic bottom wall with a second photoresist layer to height corresponding to a selected inner height of each microchannel;
• i) depositing a third adhesion layer over said substrate surface and said metallic bottom walls coated with said second photoresist layer coating thereon;
• j) depositing a second electroplating seed layer upon said third adhesion layer;
• k) selectively coating portions of said second electroplating seed layer with a third photoresist layer such that uncoated portions of said second electroplating seed layer define the locations of the underlying metallic bottom walls;
• l) electroplating said uncoated portions of said second electroplating seed layer with a selected metal to thereby form side walls and a top wall upon each bottom wall, said electroplating continuing until a desired thickness for said side walls and top walls is achieved;
• and
• m) removing said third photoresist layer and underlying portions of said second electroplating seed layer, said third adhesion layer, and said second photoresist layer to thereby hollow each said microchannel.